On Thu, Jan 16, 2020 at 6:28 AM stan <stanb@panix.com> wrote:
I am trying to create a function to automatically create a reference value when a record is inserted into a table. I want the reference value to consist of the user that is doing the insert, plus a couple of dates, plus a sequence number, where the sequence number will increment every time a given user inserts a record. because this sequence number is user specific, my first thought is not to use a set of sequences for it, but to do this by selecting the maximum sequence number that user has entered in the past.
What happens if two transactions by/for the same user are committed at around the same point in time? The advantage of sequences is they're guaranteed to be unique, I'm not sure counting the number of previous records and adding one will always assure that.